Abstract

Background Strong evidence exists for an association between
childhood trauma, particularly childhood sexual abuse, and hallucinations in
schizophrenia. Hallucinations are also well-documented symptoms in people with
bipolar affective disorder.

Aims To investigate the relationship between childhood sexual abuse
and other childhood traumas and hallucinations in people with bipolar
affective disorder.

Method A sample of 96 participants was drawn from the Medical
Research Council multi-centre trial of cognitive–behavioural therapy for
bipolar affective disorder. The trial therapists recorded spontaneous reports
of childhood sexual abuse made during the course of therapy. Symptom data were
collected by trained research assistants masked to the hypothesis.

Results A significant association was found between those reporting
general trauma (n=38) and auditory hallucinations. A highly
significant association was found between those reporting childhood sexual
abuse (n=15) and auditory hallucinations.

Conclusions The relationship between childhood sexual abuse and
hallucinations in bipolar disorder warrants further investigation.

Goodwin & Jamison
(
1990) reviewed 20 studies
conducted between 1922 and 1989 investigating the prevalence of hallucinations
in bipolar disorder and calculated a weighted mean average of 18%. To date, no
study has attempted a systematic analysis of the relationship between
childhood sexual abuse or other childhood trauma and hallucinations in people
with bipolar disorder. In this study we investigated this relationship in a
sample of patients recruited to a multi-centre, randomised, controlled trial
of cognitive–behavioural therapy.

METHOD

Participants

A total of 255 persons meeting DSM–IV
(
American Psychiatric Association,
1994) criteria for bipolar affective disorder were recruited to a
randomised, controlled trial of cognitive–behavioural therapy for
bipolar disorder. From this group 126 were randomised to receive therapy,
which was conducted by five qualified therapists supervised by internationally
recognised experts (Professor Jan Scott and Dr Peter Kinderman). Four of the
therapists agreed to complete questionnaires recording spontaneous reports of
trauma by their patients. Data were obtained for all 96 patients treated by
the four participating therapists.

Initial diagnostic assignment was made by referring consultant
psychiatrists and verified by a team of four trained graduate research
assistants who inspected case notes and interviewed the patients before
therapy and at follow-up points using the Structured Clinical Interview for
DSM–IV (SCID;
First et al,
1996). Inclusion criteria were doubly ratified diagnosis of
bipolar disorder in individuals aged 16 years or older drawn from four
geographically distinct areas of the UK. No patient reported mood-incongruent
psychotic symptoms at referral. Evidence of a lifetime history of
mood-incongruent psychotic phenomena was reported for 33 of the sample.

Recruitment by centre was as follows: Manchester 22, Liverpool 25, Glasgow
25 and Cambridge 24. Individuals with substance misuse as a primary diagnosis
or evidence of organic illness were excluded from the study, as were
individuals displaying rapid-cycling bipolar disorder or severe comorbid
borderline personality disorder. As the research assistants were employed for
the purposes of the clinical trial, they were masked to the hypothesised
relationship between trauma and hallucinations.

The sample comprised 32 men and 64 women. The minimum age was 22 years and
the maximum 70 years (mean 40.5, s.d.=10.4). Mean age at illness onset,
recorded by the research assistants on the basis of case-note and interview
data, was known for 95 participants, and found to be 24.4 years (s.d.=7.8).
Eighty-one participants had been hospitalised at some point in their illness,
and their mean age of first hospitalisation was 29.4 years (s.d.=9.4).

Measures

Participants were seen by the trial therapists for approximately 24
one-hour sessions over a 6-month period. Direct references to childhood sexual
abuse or other traumas made by participants during assessment or at other
points in therapy were collected by the therapists, who completed an
eight-item questionnaire for each patient. The questionnaire listed eight
categories of trauma: sexual abuse; physical abuse; physical abuse with a
weapon; witness to the killing or serious injury of another (including
parasuicide); having a close friend or relative who was murdered or killed
(including suicide); experiencing a significant accident; experiencing a
natural or human-made disaster; any other trauma. These categories were based
on the categorisation by Mueser et al
(
1998) of traumas commonly
experienced by those with serious mental illness, which were in turn derived
from the Trauma History Questionnaire
(
Green, 1996). For each
category, the therapists were asked to record detailed descriptions of the
traumatic event where possible.

A report of any trauma including childhood sexual abuse was only classified
as occurring in childhood if it occurred before the patient's 16th birthday.
The behavioural descriptions of childhood sexual abuse were categorised
according to the criteria used in the Child Maltreatment History Self-Report
(CMHSR;
Badgley et al,
1984), an assessment tool used in a large-scale Canadian study of
childhood sexual abuse in the general population. Sexual abuse is rated in the
CMHSR according to four distinct categories:

child exposed to on more than one occasion;

child threatened with sexual contact;

child touched sexually;

sexual assault (attempted or actual).

In our sample no participants reported threatened sexual contact only, and
in no case did the recorded onset of illness predate the reported abuse. In
order to ensure that the trauma descriptions were categorised correctly, a
psychiatric social worker with extensive experience in the assessment of
trauma and abuse (A.D.) reclassified the detailed descriptions. Interrater
reliability, indicating consensus for allocation into designated categories,
was 34/36 for recorded reports of general trauma and 15/15 for reports of
childhood sexual abuse.

Data for lifetime history of experience of psychotic symptoms were
collected by the four trained and supervised research assistants at the trial
baseline assessment, using the lifetime version of the SCID. This provided
evidence for the presence or absence of hallucinations in six distinct
categories. Only participants scoring 3 (threshold or true hallucinations) on
the baseline SCID were categorised as having a history of hallucinations; this
was to ensure that transient stress-related dissociative symptoms or
quasi-psychotic experiences of the type that may be present in borderline
personality disorder were not classified as hallucinations. To minimise the
risk of type-I statistical errors, and in accordance with our hypotheses, our
main analyses focused on hallucinations. However, to determine whether any
findings were specific to hallucinations, parallel analyses were calculated
using SCID data on patients' delusions and hallucinations in the non-auditory
modalities.

RESULTS

Forty-five participants (nearly half of the sample) had experienced
hallucinations during their lifetime: 30 had experienced auditory
hallucinations, 11 had heard voices commenting on their actions, 25 had
experienced visual hallucinations, and 9 had experienced other (tactile,
somatic or olfactory) hallucinations. The numbers of participants divulging
particular types of trauma, classified according to the Trauma History
Questionnaire categories, are given in
Table 1. Fifteen of the 96
participants disclosed some kind of childhood sexual abuse to their
therapists. No significant difference between the sexually traumatised and
non-traumatised groups was observed for the mean age at illness onset
(traumatised group 22.2 years, non-traumatised group 24.8 years;
t=1.14, two-tailed P=0.26, d.f.=93), or age at first
hospitalisation (traumatised group 28.1 years, non-traumatised group 29.6;
t=0.54, two-tailed P=0.59, d.f.=79). As both the trauma
reports and the SCID yielded categorical data, associations between trauma and
hallucinations were analysed using the chi-squared statistic.

Type of trauma spontaneously reported by patients with bipolar disorder
(n=96) to their therapists

Contingency tables showing the relationships between different kinds of
hallucination report and reports of childhood sexual abuse are shown in
Table 2. A significant
association was found between reports of any trauma and the presence or
absence of auditory hallucinations (χ2=7.61,
P<0.01, d.f.=1). The observed associations between reports of
abuse and history of any hallucinations (χ2=6.83,
P<0.005, d.f.=1), history of auditory hallucinations
(χ2=14.66, P<0.001, d.f.=1), and history of voices
commenting (χ2=14.28, P<0.002, d.f.=1) were even
more significant. However, no significant association was found between trauma
and reports of delusions, or trauma and reports of visual or tactile
hallucinations. The relationship between mood-incongruent psychotic symptoms
and childhood sexual abuse was not significant. Seven patients were diagnosed
as having borderline personality disorder. However, the observed associations
between childhood sexual abuse and hallucinations all remained when these
patients were excluded from the analyses.

Contingency table showing associations between lifetime history of
different types of hallucination and reports of childhood sexual abuse in the
sample of patients with bipolar disorder (n=96)

DISCUSSION

Previous studies of CSA and psychosis

Many studies have found that high levels of early trauma are reported by
adult psychiatric patients. In a review of 13 studies considered to be
methodologically adequate at the time, Goodman et al
(
1997) found that women
undergoing treatment for psychosis consistently reported much higher levels of
abuse than did controls. In a study of their own conducted later
(
Mueser et al, 1998)
these researchers estimated that 52% of 153 severely ill women patients they
surveyed had experienced sexual abuse during childhood, and nearly 64% had
suffered sexual abuse in later life. These figures indicate that many women
with psychosis have experienced multiple episodes of abuse. Goodman et
al (
1999) also reported
that, in a further sample of 50 patients with serious mental illness (64%
schizophrenia), three-quarters of the women and nearly half of the men had
experienced childhood sexual abuse. Similar findings were reported in a more
recent survey of first-episode patients
(
Neria et al, 2002).
In the same study, it was reported that only 5% of reports of early trauma
could be attributed to aberrant behaviour of the patient (for example, placing
themselves in high-risk situations).

Experience of early trauma has been specifically associated with
Schneiderian symptoms (
Ross et
al, 1994;
Ellason &
Ross, 1997) or hallucinations (Reid & Argyle, 1999). Other
studies have reported that psychotic symptoms, especially hallucinations, are
frequently experienced by survivors of early trauma such as sexual abuse
(
Heins et al, 1990;
Ensink, 1993) and later trauma
such as exposure to military combat (
Butler
et al, 1996).

In a community survey, Ross & Joshi
(
1992) reported that 46% of
those who reported three or more Schneiderian symptoms had experienced
childhood physical or sexual abuse, compared with 8% with no such symptoms. In
surveys of schizotypal traits in the normal population it has also been found
that reports of unusual experiences correlate with a reported history of
childhood sexual abuse (
Bryer et
al, 1987;
Startup,
1999) or childhood maltreatment
(
Berenbaum, 1999).

Given this apparent association between hallucinatory experiences and
childhood sexual abuse in people with schizophrenia, it is obviously important
to establish whether the same relationship exists between hallucinations and
childhood sexual abuse in other clinical groups.

Findings of this study

Over a quarter of the participants in our study reported visual
hallucinations, a proportion that is higher than in most previously reported
studies of people with bipolar disorder
(
Goodwin & Jamison, 1990).
However, in one of the largest studies of this kind (Black & Nazrallah,
1989), the observed prevalence rate for visual hallucinations was 27%, which
is almost identical to our own figure. In contrast to most previous studies,
the figures arrived at in our investigation were based on lifetime experiences
rather than on current symptoms.

Only 15 (16%) of our patients reported a history of childhood sexual abuse
to their therapists. This finding is comparable with those obtained from
population samples. For example, Salter
(
1988) summarised 14 North
American studies investigating childhood sexual abuse in the general
population, and reported prevalence rates ranging from 11% to 38% for women.
Despite this modest prevalence of reported abuse in our sample, strong
associations were observed between reported childhood sexual abuse and a
history of hallucinations, especially auditory ones.

Does childhood trauma cause bipolar disorder?

Although Hyun et al
(
2000) reported that a
childhood history of sexual abuse was significantly more frequent in a sample
of patients with bipolar disorder compared with a control sample of people
with major depressive disorder, the lack of appropriate control data in our
study makes it impossible for us to verify this finding. As the majority of
the participants did not report childhood sexual abuse, there is certainly
nothing in our findings to imply that bipolar affective disorder is in some
direct way caused by trauma, or that patients with this disorder are more
traumatised than other groups. Interestingly, of the 15 patients who reported
childhood sexual abuse, only three reported that the perpetrator was a blood
relative.

However, the findings are consistent with other studies which suggest that
childhood sexual abuse and other early traumas increase the risk that
individuals will experience positive symptoms, and especially hallucinations.
In our study the association between childhood sexual abuse and hallucinations
could not be attributed to borderline personality disorder, or to the presence
of mood-incongruent psychotic symptoms. In all the recorded cases of abuse in
the sample, the abuse preceded the onset of illness, including the experience
of auditory hallucinations. This observation is important because it makes it
unlikely that the abuse was imagined, or that the experience of trauma was in
some way a consequence of illness (which would be the case, for example, if
people experiencing hypomanic or manic symptoms placed themselves in
situations where there was a high risk of sexual assault).

The most plausible interpretation of the present findings is, therefore,
that childhood sexual abuse has an impact on the later symptom profile of
patients with bipolar affective disorder, increasing their vulnerability to
experiencing auditory hallucinations.

Possible mechanisms linking early trauma to hallucinations

The processes by which trauma leads to hallucinations in people with severe
mental illness are not understood. However, psychological studies have
suggested that hallucinations result from the misattribution of mental events
to an alien or external source, and that this is most likely to occur when
experiencing mental events that are automatic and low in cognitive effort
(
Bentall, 2000). As intrusive
memories of trauma are typically mental events of this kind, they may be
particularly likely to be experienced as hallucinations by individuals whose
source-monitoring abilities are compromised by severe mental illness. Negative
automatic thoughts of the kind experienced during periods of low self-esteem
would also be likely to be experienced as alien under these circumstances.
Both types of cognitive events are especially likely to be experienced during
stressful periods, especially after an adult survivor of abuse has been
further traumatised by additional negative experiences. Honig et al
(
1998) found that many people
troubled by hallucinations reported that their hallucinations began following
a retraumatising experience.

Limitations

Childhood sexual abuse was only recorded when spontaneously reported to the
therapist in this study. It is possible that the magnitude of the association
between childhood sexual abuse and hallucinations in bipolar disorder has been
underestimated by our method. Conservative criteria were used to decide
whether patients had experienced such abuse; for example, two patients with a
history of hallucinations were not classified as victims of childhood sexual
abuse because apparent behavioural descriptions of abuse obtained by the
therapists were considered ambiguous. Conversely, it may be possible that the
magnitude of the association between childhood sexual abuse and hallucinations
has been overestimated, in that we were not able to verify self-reports of
abuse with other sources such as medical or legal documents, and had to take
these self-reports at face value.

Lifetime histories of hallucinations were not validated against case-note
data. However, case notes probably provide a highly inaccurate record of these
kinds of experiences, which will be sometimes underrecorded, or sometimes
falsely recorded on the basis of ambiguous evidence (for example, patients
talking to themselves). Rosenhan
(
1973) long ago noted that
normal behaviour is sometimes misinterpreted by ward staff in this way. A
further weakness of the study was that we were unable to analyse in which mood
state hallucinations occurred, or whether auditory hallucinations in
particular occurred in the depressive or manic phase of the illness. None the
less, our findings suggest that some common mechanisms might be responsible
for the hallucinations experienced by people with schizophrenia and those
experienced by people with bipiolar affective disorder. The findings also
suggest that clinicians should be sensitive to the possibility that early
adverse experience may be an issue that needs to be addressed in the treatment
and management of hallucinating patients with bipolar disorder.

Clinical Implications and Limitations

CLINICAL IMPLICATIONS

Patients with a history of hallucinations may have experienced trauma
during childhood.

Childhood sexual abuse may play a role in the aetiology of positive
symptoms.

Patients with bipolar disorder with positive symptoms should be routinely
asked about any traumatic experiences in childhood.

LIMITATIONS

Trauma data were collected only from participants' spontaneous self-report
to therapists; and could not be verified from other sources.

Lifetime histories of hallucinations were not validated by case note
data.

Possible causal mechanisms linking trauma to later hallucinations were not
investigated.

Acknowledgments

The data for this study were collected during a clinical trial of cognitive
– behavioural therapy for bipolar disorder funded by the Medical
Research Council. Permission for the data analyses was granted by the trial
Data Management and Ethics Committee. We thank the grant holders for
encouraging publication of this paper, and especially Professor Jan Scott for
her helpful comments on an earlier draft of the manuscript. We also thank the
trial research assistants, Helen Morey, Talia Gutenstein, John Davies, Yvonne
Smith, Christine Healey, Sandi Secher, Carolyn Crane and Hazel Hayhurst, for
collecting symptom data. Particular thanks are due to the trial coordinator,
Michaela Rodger, for facilitating data retrieval.